Parton distribution functions in the pion from lattice QCD

TL;DR

This paper uses lattice QCD to analyze pion parton distribution functions, focusing on moments and chiral extrapolation, and compares results with experimental data to evaluate the potential for future precise calculations.

Contribution

It provides a detailed assessment of lattice QCD calculations of pion PDFs and discusses the prospects for improved accuracy in future studies.

Findings

Valence quark distributions agree with Drell-Yan data within errors.

Current statistical errors prevent confirmation of large-x behavior.

Future lattice QCD calculations could achieve experimental-level accuracy.

Abstract

We analyze the moments of parton distribution functions in the pion calculated in lattice QCD, paying particular attention to their chiral extrapolation. Using the lowest three non-trivial moments calculated on the lattice, we assess the accuracy with which the x dependence of both the valence and sea quark distributions in the pion can be extracted. The resulting valence quark distributions at the physical pion mass are in fair agreement with existing Drell-Yan data, but the statistical errors are such that one cannot yet confirm (or rule out) the large-x behavior expected from hadron helicity conservation in perturbative QCD. However, one can expect that the next generation of calculations in lattice QCD will allow one to extract parton distributions with a level of accuracy comparable with current experiments.